Pacific Northwest Beach Salmon Steam-Box Bake

Use case: Whole, thick fillets from large coho (“silver”) salmon cooked over a trench of coals with a lidded steam box and a wet seaweed/burlap blanket.

Revision date: December 15, 2025

Summary

This method combines two heat modes: (1) radiant heat from a coal trench (fast, “broil-like”) and (2) trapped steam generated by a seawater-wet burlap cover and wet seaweed on the lid (gentle, even cooking). For thick coho fillets, a steam-first cook followed by a short lid-cracked finish produces a moist center without overcooking the surface.

Materials and Equipment

Fresh coho salmon fillets (skin-on recommended), pinbones removed
Steam box: untreated wood (cedar/fir) with open bottom and removable lid
Rack: stainless grate or BBQ grate (avoid galvanized mesh close to high heat)
Shovel (trench), fire tools (poker/rake), heat-safe gloves
Burlap (clean) and wet seaweed/kelp for a steam blanket
Thermometer (recommended) for doneness verification
Salt, optional lemon/butter for serving

Steam Box Build Notes

Target internal width: enough to lay the fillet flat without bending.
Practical size (1–2 large fillets): about 48 in L × 18–24 in W × 18–24 in H.
Rack height: set rack about 8–10 inches above the coal plane.
Lid fit: reasonably snug is helpful, but it does not need to be airtight.

Safety note on materials

Use untreated lumber only. Avoid pressure-treated or painted wood. Prefer a stainless rack over galvanized “chicken wire” near high heat.

Site and Fire Setup

Choose location. Well above the high-tide line, away from driftwood piles and vegetation.
Dig trench. Typical: 6–8 in wide × 6–8 in deep × 36–48 in long (match the box length).
Make a coal bed. Build a fire and burn down to coals; rake coals into the trench to create a 2–4 in deep coal layer.
Stage extra coals. Keep a reserve nearby for heat refresh if wind or wet sand steals heat.

Cooking Procedure (Steam-First, Finish-Open)

Light salt the fish. Even coverage; rest 10–20 minutes if you have time.
Load the rack. Place fillets skin-side down on the rack. Prevent curling by skewering thick sections if needed.
Set the box over the trench. Center the box over the coals. Ensure the rack is 8–10 inches above the coals.
Close lid. Seat the lid.
Apply the steam blanket. Drape seawater-wet burlap over the lid, then pile wet seaweed/kelp on top. Keep it wet so it steams rather than scorches.
Steam phase (primary cook). Maintain a steady steam environment for the time suggested in the timing guide.
Finish phase (surface set). Remove seaweed/burlap. Crack the lid (or remove it briefly) to firm the surface and drive the center to final temperature.
Confirm doneness. Target 145°F / 63°C at the thickest point (recommended). Rest 3–5 minutes before serving.

Clean cook tip

Keep seawater and sand out of the fish. Use seawater only to wet the burlap/seaweed, not as a rinse on the fillets. If the beach is windy or sandy, consider placing a sheet of parchment under the fish on the rack (do not let it touch coals).

Timing Guide for Thick Coho Fillets

Times assume a strong coal bed, moderate wind, and rack height of 8–10 inches above coals. Adjust as needed.

Thickness	Steam phase	Finish phase	Notes
1.25 in	10–12 min	2–4 min	Good baseline for many coho shoulder cuts.
1.50 in	12–16 min	3–5 min	Watch belly edges; increase rack height if albumen pours out early.
1.75 in	14–18 min	4–6 min	Consider adding more coals under the thickest section only.
2.00 in	16–20 min	5–7 min	Best results with steam-first; avoid “all-finish” cooking for thick fillets.

Doneness Checks

Temperature: 145°F / 63°C at the thickest point (recommended).
Visual: opaque flesh that flakes with gentle pressure; surface oil shimmering.
Albumen: a light amount is normal; heavy white runoff often indicates excessive heat.

Safety and Environmental Notes

Fire rules: verify local beach fire regulations and any seasonal burn bans before lighting a fire.
Tide: set up well above the high-tide line and monitor rising water.
Materials: untreated wood only; avoid treated lumber and questionable scrap.
Seaweed collection: rules vary by location; if unsure, bring a wet cover and use clean water with a pinch of salt.
Food safety: keep fish cold until cooking; avoid cross-contamination.